Devices including vias extending through alternating dielectric materials and conductive materials, and related electronic devices

ABSTRACT

A semiconductor device includes a capacitor structure. The capacitor structure comprises conductive vias extending through openings in a stack of alternating dielectric materials and first conductive materials, each conductive via comprising a second conductive material extending through the openings and another dielectric material on sidewalls of the openings, first conductive lines in electrical communication with a first group of the conductive vias, and second conductive lines in electrical communication with a second group of the conductive vias. Related semiconductor device, electronic systems, and methods are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/524,994, filed Jul. 29, 2019, now U.S. Pat. No. 10,756,014, issuedAug. 25, 2020, which is a continuation of U.S. patent application Ser.No. 15/687,830, filed Aug. 28, 2017, now U.S. Pat. No. 10,373,904,issued Aug. 6, 2019, the disclosure of each of which is herebyincorporated herein in its entirety by this reference.

TECHNICAL FIELD

Embodiments disclosed herein relate to semiconductor devices includingcapacitors arranged in series that may be used to capacitively couple afirst component to a second component of a system (e.g., a semiconductordevice, an integrated circuit, etc.). More particularly, embodiments ofthe disclosure relate to semiconductor devices and integrated circuitsincluding capacitors comprising a conductive via extending throughalternating conductive materials and dielectric materials, to relatedintegrated circuits and electronic systems including such semiconductordevices, and to related methods.

BACKGROUND

A continuing goal of the semiconductor industry has been to increase thememory density (e.g., the number of memory cells per memory die) ofmemory devices, such as non-volatile memory devices (e.g., NAND Flashmemory devices). One way of increasing memory density in non-volatilememory devices is to utilize a vertical memory array (also referred toas a “three-dimensional (3D) memory array”) architecture. A conventionalvertical memory array includes semiconductor pillars extending throughopenings in tiers of conductive structures (e.g., control gates, accesslines, etc.) and dielectric materials at each junction of thesemiconductor pillars and the conductive structures. Such aconfiguration permits a greater number of transistors to be located in aunit of die surface area by building the array upwards (e.g.,vertically) on a die, as compared to structures with conventional planar(e.g., two-dimensional) arrangements of transistors.

Conventional vertical memory arrays include tiers of conductivestructures (e.g., access lines, word lines, etc.) separated bydielectric material. Some conventional vertical memory arrays requirecapacitors for operably coupling one or more components of the verticalmemory array to one another, such as to reduce noise between two buses(e.g., between a power bus and a ground bus). Forming capacitors in suchmemory arrays requires additional real estate on the semiconductordevice. In some embodiments, capacitors may be formed by directlycontacting conductive word line materials to form an electrical contact,such as by forming electrical contacts to individual levels of the wordline materials with a so-called “stair-step” structure. However, thestair-step structures may consume a significant amount of real estate,often larger than that available for the capacitor. In some instances,due to the real estate required to electrically contact the word lines,only a portion of the available word line levels are contacted for acapacitor structure.

In addition to requirements to increase memory density and reduce thesize of memory arrays, it is a goal to reduce the footprint of otherportions of semiconductor devices, such as at peripheral regions ofsemiconductor devices. By way of nonlimiting example, it is a goal toreduce the size of portions of a semiconductor die peripheral to amemory array, such as portions that may be coupled to sub-arrayfeatures, power buses, ground buses, charge pumps, a power sidedecoupling capacitor, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a semiconductor device including conductive viasin a via region of the semiconductor device, according to embodiments ofthe disclosure;

FIG. 2 is an enlarged top view of a portion of the semiconductor deviceof FIG. 1, taken from dashed box A of FIG. 1;

FIG. 3 is a partial cross-sectional view of the semiconductor device ofFIG. 1 and FIG. 2, taken from section line 3-3 in FIG. 1;

FIG. 4 is a detailed cross-sectional view of a portion of thesemiconductor device of FIG. 1 through FIG. 3, taken from dashed box Bin FIG. 3;

FIG. 5A and FIG. 5B are simplified schematics illustrating a capacitorstructure formed by capacitors, according to embodiments of thedisclosure;

FIG. 6A and FIG. 6B are cross-sectional views of a semiconductor deviceillustrating a method of forming the semiconductor device, according toembodiments of the disclosure;

FIG. 7 is a simplified schematic of a system including at least onesemiconductor device, according to embodiments of the disclosure; and

FIG. 8 is a simplified block diagram of a system implemented accordingto embodiments of the disclosure.

DETAILED DESCRIPTION

The illustrations included herewith are not meant to be actual views ofany particular systems, semiconductor structures, or semiconductordevices, but are merely idealized representations that are employed todescribe embodiments herein. Elements and features common betweenfigures may retain the same numerical designation except that, for easeof following the description, for the most part, reference numeralsbegin with the number of the drawing on which the elements areintroduced or most fully described.

The following description provides specific details, such as materialtypes, material thicknesses, and processing conditions in order toprovide a thorough description of embodiments described herein. However,a person of ordinary skill in the art will understand that theembodiments disclosed herein may be practiced without employing thesespecific details. Indeed, the embodiments may be practiced inconjunction with conventional fabrication techniques employed in thesemiconductor industry. In addition, the description provided hereindoes not form a complete description of a capacitor structure, asemiconductor device, or an integrated circuit or a complete descriptionof a process flow for manufacturing a capacitor structure, asemiconductor device, or an integrated circuit. The structures describedbelow may not form complete capacitor structures, semiconductor devices,or integrated circuits. Only those process acts and structures necessaryto understand the embodiments described herein are described in detailbelow. Additional acts to form a complete capacitor structure,semiconductor device or integrated circuit may be performed byconventional techniques.

According to embodiments disclosed herein, a semiconductor device mayinclude a capacitor structure extending through a stack of alternatingconductive materials and dielectric materials. The capacitor structuremay include at least two capacitors that are operably connected in aseries configuration. The capacitor structure may include a firstterminal comprising a first electrically conductive lead in electricalcommunication with a first set of conductive lines, which may be inelectrical communication with a first group of conductive vias. A secondterminal of the capacitor may include a second electrically conductivelead in electrical communication with a second set of conductive lines,which may be in electrical communication with a second group of theconductive vias. The conductive vias may extend though the stack ofalternating conductive material and dielectric material and may includea dielectric material on sidewalls thereof and a conductive materialextending therethrough. The first group of conductive vias and thesecond group of conductive vias may be electrically isolated from eachother (i.e., may not be in direct electrical contact with each other).For example, the first group of conductive vias and the second group ofconductive vias may be isolated at least by the dielectric materialsbetween them (e.g., the dielectric materials on sidewalls thereof). Eachconductive via may define capacitors, a capacitor (e.g., at least onecapacitor (e.g., two capacitors)) defined at each region (e.g., level)of the alternating conductive material through which the conductive viaextends. The conductive vias of the first group may form a firstcapacitor and the conductive vias of the second group may form a secondcapacitor located in series with the first capacitor. The firstelectrically conductive lead may be in electrical communication with afirst component of a semiconductor device and the second electricallyconductive lead may be in electrical communication with a secondcomponent of the semiconductor device to capacitively couple the firstcomponent of the semiconductor device to the second component of thesemiconductor device. The first component and the second component mayinclude any component of a semiconductor device or integrated circuitrythat may be electrically coupled together by a capacitor, such as, byway of nonlimiting example, one or more of a decoder (e.g., a word linedecoder), an encoder, a multiplexer, a ground bus, a power bus, sensingcircuitry, an amplifier, a driver, communication circuitry, or anothercomponent. The capacitor structure may comprise a charge pump, adecoupling capacitor, etc. Since the capacitor structure may extendthrough multiple regions (e.g., levels) of alternating dielectricmaterial and conductive material, the capacitor structure may exhibit arelatively high capacitance (e.g., a capacitance that is proportional tothe depth of the conductive vias forming the capacitor structures).

The capacitor structure may be formed in any region including highaspect ratio openings through at least some electrically conductivematerials, the openings lined with a dielectric liner on sidewallsthereof and subsequently filled with a conductive material. In someembodiments, the capacitor structure may be formed in alternatingregions of dielectric material and conductive material, such as in 3DNAND semiconductor devices. In some such embodiments, the capacitorstructure may be formed in regions of the dielectric material andconductive material that are used to form vertical memory cells and maybe electrically isolated from the memory cells. Since the capacitorstructure utilizes materials that are present in the memory array, thecapacitor structure may not utilize as much real estate in thesemiconductor device as would conventional capacitor structuresexhibiting the same capacitance of the capacitor structure. In addition,because the capacitor structure may not include a direct electricalconnection to each region (e.g., level) of the alternating conductivematerials of the stack, a separate electrical contact and landing pad toeach region of the conductive material may not be required for thecapacitor, further reducing a real estate requirement of the capacitorstructure.

FIG. 1 is a schematic top view of a semiconductor device 100, accordingto embodiments of the disclosure. The semiconductor device 100 depictedin FIG. 1 does not show all features of the semiconductor device 100such that underlying structures and elements can be seen more clearly.FIG. 2 shows an enlarged top view of a portion of the semiconductordevice 100, taken from dashed box A of FIG. 1. FIG. 3 shows a partialcross-sectional view of the semiconductor device 100 of FIG. 1, takenalong section line 3-3.

Referring to FIG. 1, the semiconductor device 100 may include a memoryarray region 102 and a peripheral region that may include, for example,a stair-step region 104 at one or both longitudinal ends of thesemiconductor device 100 and a via region 106, which may be locatedlongitudinally between the memory array region 102 and the stair-stepregions 104. Slots 114 (shown in FIG. 1 as solid lines), may be filledwith a dielectric material (e.g., a silicon oxide material), and mayextend through the semiconductor device 100 in the memory array region102 proximate to and between adjacent memory cell pillars 108.

The memory array region 102 may include an array of memory cell pillars108, each memory cell pillar 108 extending vertically through thesemiconductor device 100. In some embodiments, the memory array mayinclude a vertical NAND structure. By way of nonlimiting example, eachof the memory cell pillars 108 may include a central region 110 (seeFIG. 3) of a semiconductor material, such as a polysilicon orsilicon-germanium material, at least partially surrounded by a chargetrapping material 112 (FIG. 3), such as an oxide-nitride-oxide (“ONO”)material. Memory cell pillars 108 are known in the art and are,therefore, not described in detail herein.

Electrically conductive access lines (e.g., word lines) 116 may extendalong the slots 114 and may electrically couple to the memory cellpillars 108 to form individual memory cells.

The stair-step region 104 may include one or more stair-step structures122 for electrically contacting and accessing different overlappingconductive access lines 116. The stair-step structures 122 may includecontact regions 124 (e.g., “stairs”) (for clarity, labeled at the topportion of FIG. 1, but also present in the bottom portion of FIG. 1)arranged like a staircase. Word line contacts 126 (for clarity, shownand labeled at the bottom portion of FIG. 1, but also present in the topportion of the semiconductor device 100 in FIG. 1) may physically andelectrically contact the contact regions 124 of the stair-stepstructures 122 to provide electrical access to the conductive accesslines 116.

In some embodiments, the stair-step region 104 includes conductive vias120 that may extend through the semiconductor device 100. Since theconductive vias 120 extend through the semiconductor device 100, theymay also be referred to as “through-array vias” or “TAVs.” Electricalconnections 128 may electrically connect the conductive access lines 116to the conductive vias 120.

The conductive access lines 116 may be formed of a material withsufficient electrical conductivity to access the memory cells of thememory cell pillars 108 and to provide electrical communication betweenthe word line contacts 126 and the electrical connections 128. By way ofnonlimiting example, the conductive access lines 116 include aluminum,copper, nickel, chromium, cobalt, ruthenium, rhodium, palladium, silver,platinum, gold, iridium, tantalum, tungsten, conductive metal nitrides(e.g., TiN, TaN, WN, etc.), conductive metal silicides (e.g., tantalumsilicides, tungsten silicides, nickel silicides, titanium silicides,etc.), polysilicon, and combinations thereof. In some embodiments, theconductive access lines 116 comprise tungsten.

Although the semiconductor device 100 has been illustrated as includingthe stair-step structures 122, it is contemplated that in otherembodiments, the semiconductor device 100 does not include thestair-step structure 122.

Conductive vias 130 may be located proximate the memory array region102, such as in the via region 106. The conductive vias 130 may bestructured and configured to form a capacitor structure having asuitable capacitance for operation of the semiconductor device 100, aswill be described herein.

FIG. 2 is a top view of an enlarged portion of the semiconductor device100, illustrating dashed box A in FIG. 1. The illustrated portion of thesemiconductor device 100 in FIG. 2 corresponds to the via region 106 inFIG. 1. FIG. 3 is a simplified cross-sectional view of a portion of thesemiconductor device 100 taken along section line 3-3 in FIG. 1.

Referring to FIG. 3, the memory cell pillars 108 may vertically extendthrough a stack of alternating conductive access lines 116 anddielectric materials 132 disposed over a substrate 101. An individualmemory cell may be formed at each junction between the respectiveconductive access lines 116 and memory cell pillars 108.

The substrate 101 may be a semiconductor substrate, a base semiconductormaterial on a supporting substrate, a metal electrode, or asemiconductor substrate having one or more materials, structures, orregions formed thereon. The substrate 101 may be a conventional siliconsubstrate or other bulk substrate including semiconductor material. Asused herein, the term “bulk substrate” means and includes not onlysilicon wafers, but also silicon-on-insulator (“SOI”) substrates, suchas silicon-on-sapphire (“SOS”) substrates or silicon-on-glass (“SOG”)substrates, epitaxial layers of silicon on a base semiconductorfoundation, or other semiconductor or optoelectronic materials, such assilicon-germanium (Sii-xGex, where x is, for example, a mole fractionbetween 0.2 and 0.8), germanium (Ge), gallium arsenide (GaAs), galliumnitride (GaN), or indium phosphide (InP), among others. Furthermore,when reference is made to a “substrate” in the following description,previous process stages may have been utilized to form material,regions, or junctions in the base semiconductor structure or foundation.The substrate 101 may include one or more materials associated withintegrated circuitry fabrication. Such materials may include, forexample, one or more refractory metals, barrier materials, diffusionmaterials, insulative materials, etc. The substrate 101 may include, forexample, complementary metal oxide semiconductor (CMOS) structures, orother semiconductor structures.

The via region 106 may be electrically isolated from other portions ofthe semiconductor device 100 by one or more trenches 140 that may befilled with an electrically insulative material (e.g., a dielectricmaterial) 142. The insulative material 142 may include silicon oxide(e.g., silicon dioxide), silicon nitride (e.g., Si₃N₄), siliconoxynitride, spin-on dielectric materials, tetraethyl orthosilicate(TEOS), borophosphosilicate (BPS), phosphosilicate glass (PSG), andcombinations thereof.

The via region 106 may include the conductive vias 130, which may extendthrough the semiconductor device 100. The conductive vias 130 may beelectrically isolated from the memory array region 102 and from otherportions of the semiconductor device 100 by one or more of the trenches140. In some embodiments, the trench 140 may extend from a surface ofthe semiconductor device 100 to the substrate 101 over which the memorycell pillars 108 and the conductive via 130 may be formed. In otherembodiments, the trench 140 may extend only partially through thesemiconductor device 100.

In some embodiments, one or more trenches 140 may electrically isolateone or more groups of conductive vias 130. In some embodiments, theconductive vias 130 may be disposed within an enclosure defined by thetrenches 140, as illustrated in FIG. 2. However, the disclosure is notso limited and the conductive vias 130 may be separated from the memoryarray region 102 by, for example, only one trench 140 between theconductive vias 130 and the memory array region 102. In some suchembodiments, the trench 140 may extend between only the memory arrayregion 102 and the via region 106.

The conductive vias 130 may be disposed over a source material 170 (FIG.2), such as a source select gate material that may be used in a NANDsemiconductor device. The source material 170 may include a conductivematerial such as, for example, polysilicon.

The conductive vias 130 may be arranged in rows and columns within thevia region 106. Although FIG. 2 illustrates five rows of conductive vias130 and four columns of conductive vias 130, the disclosure is not solimited. In other embodiments, the semiconductor device 100 may includefewer or more conductive vias 130, depending on a particular application(e.g., a desired capacitance) for the conductive vias 130.

The conductive vias 130 in at least some of the columns of theconductive vias 130 may be in electrical communication with each othervia one or more first conductive lines 144. Conductive vias 130 in atleast other of the columns of conductive vias 130 may be in electricalcommunication with each other via one or more second conductive lines146. The first conductive lines 144 may be in electrical communicationwith a first electrically conductive lead 148 and the second conductivelines 146 may be in electrical communication with a second electricallyconductive lead 150. For example, a first group of conductive vias 130may be in electrical communication with the first electricallyconductive lead 148 and at least a second group of conductive vias 130may be in electrical communication with the second electricallyconductive lead 150. In some embodiments, about half of the conductivevias 130 are in electrical communication with the first conductive lines144 and about half of the conductive vias 130 are in electricalcommunication with the second conductive lines 146. In some suchembodiments, capacitors formed from the first group of the conductivevias 130 may exhibit substantially the same capacitance as capacitorsformed from the second group of conductive vias 130.

Although FIG. 2 illustrates that every other column of conductive vias130 is in electrical communication with a first conductive line 144 andthe other columns of conductive vias 130 are in electrical communicationwith a second conductive line 146, the disclosure is not so limited. Inother embodiments, electrical contacts between the conductive vias 130and the first conductive lines 144 and second conductive lines 146 maybe other than those illustrated.

Although FIG. 2 illustrates that rows and columns of the conductive vias130 are arranged perpendicular to each other, the disclosure is not solimited. In some embodiments, the conductive vias 130 may be arranged inrows and columns that may not be arranged parallel or perpendicular toeach other. By way of nonlimiting example, the conductive vias 130 maybe arranged in rows that are oriented at an angle other than about 90°with respect to columns of the conductive vias 130. In otherembodiments, the conductive vias 130 may be arranged in a randompattern.

Although FIG. 2 illustrates the conductive vias 130 as having a squareshape, the disclosure is not so limited. In other embodiments, theconductive vias 130 may have a circular shape or another shape.

Referring to FIG. 3, the conductive vias 130 may include a conductivematerial 136 extending through openings formed in a stack of alternatingregions (e.g., levels) of conductive materials 134 and the dielectricmaterials 132. The conductive vias 130 may extend through the stack ofalternating regions of conductive materials 134 and alternatingdielectric materials 132 in a direction that is substantiallyperpendicular to a direction in which the alternating conductivematerials 134 and alternating dielectric materials 132 extend.

Each region of conductive material 134 may be disposed over a region ofthe dielectric material 132, which in turn, may be disposed over anotherregion of the conductive material 134. Stated another way, each regionof conductive material 134 may be disposed between regions of thedielectric material 132 and each region of the dielectric material 132may be disposed between regions of the conductive material 134.

The conductive material 134 may include the same material as theconductive access lines 116. By way of nonlimiting example, theconductive material 134 may include aluminum, copper, nickel, chromium,cobalt, ruthenium, rhodium, palladium, silver, platinum, gold, iridium,tantalum, tungsten, conductive metal nitrides (e.g., TiN, TaN, WN,etc.), conductive metal silicides (e.g., tantalum silicides, tungstensilicides, nickel silicides, titanium silicides, etc.), polysilicon, andcombinations thereof. In some embodiments, the conductive material 134comprises tungsten. As will be described herein, the conductive material134 may be formed concurrently with formation of the conductive accesslines 116.

A dielectric material 138 may overlie sidewalls of the conductive via130. The dielectric material 138 may also be referred to herein as a“dielectric liner.” The dielectric material 138 may be disposed betweenthe conductive material 136 and each of the regions of the dielectricmaterial 132 and the conductive material 134. Stated another way, thedielectric material 138 may separate and electrically insulate theconductive material 136 of each conductive via 130 from the alternatingregions of the conductive material 134.

The dielectric material 138 may include any material for electricallyinsulating the conductive material 134 of the regions of conductivematerial 134 from the conductive material 136 of the conductive vias130. By way of nonlimiting example, the dielectric material 138 mayinclude silicon oxide (e.g., silicon dioxide), silicon nitride (e.g.,Si₃N₄), silicon oxynitride, spin-on dielectric materials, tetraethylorthosilicate (TEOS), borophosphosilicate (BPS), phosphosilicate glass(PSG), and combinations thereof. In some embodiments, the dielectricmaterial 138 includes the same material as the dielectric material 132of the alternating regions of dielectric material 132. In someembodiments, the dielectric material 138 includes silicon dioxide.

An insulative material 152 may overlie the conductive vias 130 and thememory cell pillars 108. With reference to FIG. 2 and FIG. 3, the firstconductive lines 144 and the second conductive lines 146 may extendthrough the insulative material 152 (not shown in FIG. 2 for clarity).As described above and as illustrated in FIG. 2, the first conductivelines 144 may be electrically connected to the first electricallyconductive lead 148 and the second conductive lines 146 may beelectrically connected to the second electrically conductive lead 150.

FIG. 3 illustrates five overlying regions (e.g., levels) of conductivematerial 134 in the via region 106 (and five conductive access lines 116in the memory array region 102) and five overlying first dielectricmaterials 132. Thus, the semiconductor device 100 shown in FIG. 3 hasfive tiers. However, the present disclosure is not limited tosemiconductor devices 100 having five tiers. Rather, the semiconductordevice 100 may include any number of tiers, such as at least about 16,at least about 32, at least about 36, at least about 64, at least about72, or at least about 128 tiers. In other words, in some embodiments,the semiconductor device 100 may include at least about 128 sets ofalternating conductive material 134 and dielectric material 132 (e.g.,at least about 128 regions of conductive material 134 and about 128regions of dielectric material 132). Similarly, the semiconductor device100 may include at least about 128 sets of alternating conductive accesslines 116 and dielectric material 132. In some embodiments, thesemiconductor device 100 includes the same number of tiers in the memoryarray region 102 as the number of tiers in the via region 106.

In some embodiments, a total number of tiers of the semiconductor device100 may have a height of about 4 μm or greater, such as at least about 4μm, at least about 6 μm, or at least about 8 μm. Accordingly, in somesuch embodiments, the conductive vias 130 may extend through at leastabout 4 μm or more of alternating regions of conductive materials 134and dielectric materials 132.

Although FIG. 2 illustrates that the first conductive lines 144, thesecond conductive lines 146, the first electrically conductive lead 148,and the second electrically conductive lead 150 extend over theconductive vias 130, the disclosure is not so limited. In otherembodiments, the first conductive lines 144, the second conductive lines146, the first electrically conductive lead 148, and the secondelectrically conductive lead 150 may electrically contact the conductivevias 130 through the substrate 101. In some embodiments, the firstconductive lines 144 may extend over the conductive vias 130 and thesecond conductive lines 146 may extend below the conductive vias 130.

FIG. 4 is an enlarged portion illustrating a cross-section of aconductive via 130. The conductive via 130 extending through thedielectric materials 132 and the conductive materials 134 may form aplurality of capacitors 160 that may be arranged in series with respectto each other. Each capacitor 160 may be defined by the conductivematerial 136 of the conductive via 130, the dielectric material 138 onsidewalls of the conductive via 130, and each region of the conductivematerial 134. Since each conductive material 134 region is separatedfrom other conductive material 134 regions by the dielectric material132 regions, each region of the conductive material 134 may define oneor more capacitors 160 distinct from and electrically insulated fromcapacitors 160 of other regions of the conductive material 134. In otherwords, each capacitor 160 may be defined by a capacitor plate comprisinga portion of the conductive material 136 of the conductive via 130, adielectric material comprising the dielectric material 138, and anothercapacitor plate comprising a region of the conductive material 134. Aconductive material 134 between adjacent conductive vias 130 maycomprise a capacitor plate of two separate capacitors 160.

A number of capacitors 160 associated with each conductive via 130 maycorrespond to a number of conductive material 134 regions through whichthe conductive via 130 extends. By way of nonlimiting example, there maybe two capacitors 160 associated with the conductive via 130 for eachregion of conductive material 136 through which the conductive via 130extends (e.g., one on each side of the conductive via 130). Accordingly,there are six capacitors 160 illustrated in the cross-sectional view ofFIG. 4. Since each conductive via 130 may extend through, for example,128 conductive material 134 regions, there may be 256 capacitors 160associated with each conductive via 130. Accordingly, the conductivematerial 136 of the conductive via 130 may be capacitively coupled toeach conductive material 134 region through the dielectric material 138on the sidewalls of the conductive via 130. Each capacitor 160associated with a particular conductive via 130 may be capacitivelycoupled to other capacitors 160 associated with the same conductive via130 in a series configuration.

A thickness T of the dielectric material 138 on sidewalls of theconductive via 130 may be sufficient to provide electrical stability atvoltages to which the capacitors 160 may be subjected during use andoperation. In some embodiments, the dielectric material 138 may besubjected to a voltage as high as about 30 V. The thickness of thedielectric material 138 may be between about 10 nm and about 50 nm, suchas between about 10 nm and about 20 nm, between about 20 nm and about 30nm, between about 30 nm and about 40 nm, or between about 40 nm andabout 50 nm. In some embodiments, the thickness of the dielectricmaterial 138 may be between about 25 nm and about 35 nm, such as about30 nm.

Although FIG. 1 through FIG. 3 have depicted the conductive vias 130 asbeing located in the array region 106, the disclosure is not so limited.In other embodiments, the conductive vias 130 may be located in thememory array region 102, the stair-step region 104, or both. In someembodiments, at least some of the conductive vias 130 may be located inthe via region 106, at least some of the conductive vias 130 may belocated in the stair-step region 104 or the memory array region 102.

FIG. 5A is a simplified schematic illustrating a capacitor structure 200that may be formed by the capacitors 160 (FIG. 4) of the conductive vias130. The capacitor structure 200 may include the first electricallyconductive lead 148 that may be operably coupled to a first component202 of integrated circuitry. The first electrically conductive lead 148may be in electrical communication with one or more of the firstconductive lines 144, which in turn, may be operably coupled to one ormore conductive vias 130 (FIG. 3, FIG. 4).

As described above, each conductive via 130 may comprise a portion ofcapacitors 160, each capacitor 160 comprising a portion of theconductive material 136 of the conductive via 130, the dielectricmaterial 138, and the conductive material 134 of each region. The firstconductive lines 144 may be in electrical communication with the secondconductive lines 146 through the conductive materials 134. Statedanother way, each capacitor 160 located along a conductive material 136of a conductive via 130 may be in electrical communication with arespective conductive material 134 since the conductive material 134 maycomprise a capacitor plate of the respective capacitor.

The second conductive lines 146 may be in electrical communication withthe second electrically conductive lead 150, which may be in electricalcommunication with a second component 204 of the integrated circuitry.

In use and operation, a current may flow from the first component 202 tothe first electrically conductive lead 148. The current may flow fromthe first electrically conductive lead 148 to one or more of the firstconductive lines 144, which may be arranged in a parallel configurationwith respect to each other. The current may flow from each firstconductive line 144 through one or more conductive vias 130 inelectrical communication with the respective first conductive line 144.

Since each conductive via 130 includes a plurality of capacitors 160formed by the conductive material 136 extending through the conductivevia 130, the dielectric material 138, and the conductive material 134,each conductive via 130 may exhibit a capacitance that is equivalent toa capacitance of the plurality of capacitors 160 arranged in a seriesconfiguration. Since the first conductive lines 144 are arranged inparallel with respect to each other, the conductive vias 130 inelectrical communication with the first conductive lines 144 may exhibita capacitance of capacitors arranged in a parallel configuration.

The electrical current may flow through each conductive material in thestack of alternating conductive materials 134 to an adjacent conductivevia 130. The adjacent conductive vias 130 may exhibit a similarconfiguration as the conductive vias 130 in electrical communicationwith the first conductive lines 144, but may be in electricalcommunication with the second conductive lines 146.

Since the adjacent conductive vias 130 include a plurality of capacitors160 formed by the conductive material 136 extending through theconductive via 130, the dielectric material 138, and the conductivematerial 134 regions, each conductive via 130 in electricalcommunication with the second conductive lines 146 may exhibit acapacitance that is equivalent to a capacitance of capacitors arrangedin series, similar to the conductive vias 130 in electricalcommunication with the first conductive lines 144. Since the secondconductive lines 146 are arranged in parallel with respect to eachother, the conductive vias 130 in electrical communication with thesecond conductive lines 146 may exhibit a capacitance of capacitorsarranged in a parallel configuration. Accordingly, with reference toFIG. 5B, a first capacitor 162 may be capacitively coupled to a secondcapacitor 164 in series. The first capacitor 162 may be defined by thecapacitors 160 in electrical communication with the first conductivelines 144 and the first electrically conductive lead 148 and the secondcapacitor 164 may be defined by the capacitors 160 in electricalcommunication with the second conductive lines 146 and the secondelectrically conductive lead 150.

The current may flow through the second conductive lines 146 to thesecond electrically conductive lead 150, which may be in electricalcommunication with the second component 204. The second component 204may include a component that may be used in integrated circuitry of asemiconductor device that may be capacitively coupled to the firstcomponent 202 through the capacitor structure 200. By way of nonlimitingexample, each of the first component 202 and the second component 204may independently comprise a decoder, an encoder, a multiplexer, aground bus, a power bus, sensing circuitry, an amplifier, a driver,communication circuitry, another component of a semiconductor device,and combinations thereof.

The capacitor structure 200 may be used in the semiconductor device 100(FIG. 1) and integrated circuitry used to capacitively couple componentsof the semiconductor device 100 together. By way of nonlimiting example,the capacitor structure 200 may comprise a decoupling capacitor (e.g.,an on-chip decoupling capacitor) that may be coupled between, forexample, a power supply bus and a ground bus. In other embodiments, thecapacitor structure 200 may be used as a charge pump. However, thedisclosure is not so limited and the capacitor structure 200 may be usedto capacitively couple any two components of integrated circuitry.

The capacitor structure 200 may exhibit a capacitance that isproportional to the number of regions of conductive material 134 throughwhich the conductive vias 130 extend and to the number of the conductivevias 130. Since a current may flow from the first electricallyconductive lead 148 to the second electrically conductive lead 150, theregions of the conductive material 134 may not be electrically contactedto a power source. Accordingly, the conductive material 134 regions mayform capacitor structures without forming individual electrical contactsto each conductive material 134 region (such as with a stair-stepstructure) as may be required in conventional capacitor structures. Inother words, individual regions of the conductive material 134 may notbe wired. In some such embodiments, the conductive material 134 regionsmay be said to be so-called “floating” conductive material 134 regions.Accordingly, each region of the conductive material 134 may be directlycontacted and substantially surrounded by a dielectric material (e.g.,the regions of dielectric material 132, the dielectric material 142 ofthe trench 140, or another dielectric material.

Accordingly, the electrical current may flow from a capacitor structure200 of a conductive via 130 in electrical communication with the firstelectrically conductive lead 148 to a capacitor structure 200 of asecond conductive via 130 in electrical communication with the secondelectrically conductive lead 150 through the conductive material 134region. In other words, the conductive material 134 region may bridgecapacitors 160 of adjacent conductive vias 130, which adjacentconductive vias 130 may be in electrical communication with a differentone of the first electrically conductive lead 148 and the secondelectrically conductive lead 150. In some embodiments, as a number ofconductive access lines 116 of a memory cell array increases, thecapacitor structure 200 may be formed with a greater capacitance withoutrequiring additional real estate, since the capacitance of the structuremay increase with an increasing number of regions of the conductivematerial 134 region.

In some embodiments, the capacitor structure 200 may exhibit acapacitance per unit area of between about 2 femtofarads (fF)/μm² andabout 10 fF/μm², such as between about 2 fF/μm² and about 4 fF/μm²,between about 4 fF/μm² and about 6 fF/μm², between about 6 fF/μm² andabout 8 fF/μm², or between about 8 fF/μm² and about 10 fF/μm². Since thecapacitor structure 200 may include a plurality of capacitors arrangedin a series configuration, the capacitance per unit area of thecapacitor structure 200 may increase with an increasing depth of theconductive vias 130.

Accordingly, the stack of alternating conductive materials 134 anddielectric materials 132 may be used in the via region 106 (FIG. 1) toform the capacitor structure 200 (FIG. 5A, FIG. 5B). The alternatingconductive materials 134 may comprise the same material as theconductive access lines 116 (FIG. 3) that may be used to accessindividual memory cells of the memory cell pillars 108 (FIG. 3) in thememory array region 102. By way of comparison, conventionalsemiconductor devices may require additional space and materials to forma capacitor. For example, conventional semiconductor device may requireadditional real estate to form a capacitor structure. The capacitorstructure 200 may be formed directly proximate the memory array region102 and may include the same materials that are used to form the memoryarray region 102, such as the memory cell pillars 108.

In some embodiments, since the capacitor structure 200 includes thefirst capacitor 162 and the second capacitor 164 arranged in series, thecapacitor structure 200 may exhibit a substantial capacitance, even if adielectric material 138 of a conductive via 130 fails.

Accordingly, in some embodiments, a semiconductor device comprises acapacitor structure comprising conductive vias extending through a stackof alternating dielectric materials and first conductive materials, eachconductive via comprising a second conductive material extending throughthe stack within another dielectric on a sidewall of the conductive via,a first conductive line in electrical communication with a first groupof the conductive vias, and a second conductive line in electricalcommunication with a second group of the conductive vias.

Accordingly, in some embodiments, a semiconductor device comprises afirst component of an integrated circuit, a second component of theintegrated circuit, and a capacitor structure between the firstcomponent of the integrated circuit and the second component of theintegrated circuit. The capacitor structure comprises conductive viasextending through alternating first dielectric materials and firstconductive materials, each conductive via including a second dielectricmaterial on a sidewall thereof and a central portion comprising a secondconductive material, and capacitors each defined by a portion of thesecond conductive material, the second dielectric material, and oneregion of the first conductive material.

FIG. 6A and FIG. 6B illustrate a method of forming the capacitorstructure 200 (FIG. 5A, FIG. 5B). FIG. 6A is a cross-sectional view of asemiconductor device 300 including a stack 304 of alternating firstdielectric materials 332 and second dielectric materials 333 arranged inregions formed over a substrate 301, which may be the same as thesubstrate 101 described above with reference to FIG. 3. The firstdielectric material 332 may be, for example, an oxide material, such assilicon dioxide. The second dielectric material 333 may be, for example,a nitride material exhibiting an etch selectivity with respect to thefirst dielectric material 332, such as silicon nitride. The stack 304may extend over a memory array region 302 and at least a via region 306of the semiconductor device 300. The materials of the capacitorstructure 200 may be formed by conventional techniques including, butnot limited to, atomic layer deposition (ALD), chemical vapor deposition(CVD), physical vapor deposition (PVD), plasma enhanced chemical vapordeposition (PECVD), low pressure chemical vapor deposition (LPCVD), orother suitable process.

Memory cell pillars 308 may be formed in the memory array region 302,each of which memory cell pillars 308 may include a central region 310of a semiconductor material, surrounded by a charge trapping material312. By way of nonlimiting example, the memory cell pillars 308 may beformed by anisotropically removing (e.g., etching) portions of the firstdielectric material 332 and second dielectric material 333 to formopenings (e.g., holes) through the stack 304, after which the chargetrapping material 312 may be formed along sidewalls defining theopenings. The charge trapping material 312 may include, for example, anoxide, a nitride, and an oxide material (e.g., an “ONO” material). Asemiconductor material may be disposed in the remaining portions of theopenings to fill the openings and form the central region 310 of thememory cell pillars 308.

Conductive vias 330 may be formed in the via region 306, each of whichmay include a conductive material 336 disposed therein and a dielectricmaterial 338 on sidewalls thereof. By way of nonlimiting example, theconductive vias 330 may be formed by anisotropically removing (e.g.,etching) portions of the first dielectric material 332 and the seconddielectric material 333 to form openings through the stack 304 in thevia region 306. In some embodiments, the portions of the firstdielectric material 332 and the second dielectric material 333 may beremoved from the via region 306 at the same time as portions of thefirst dielectric material 332 and the second dielectric material 333 areremoved from the memory array region 302. The conductive vias 330 may beformed on landing pads of a source material 370, which may besubstantially the same as the source material 170 described above withreference to FIG. 2 and FIG. 3.

After forming the openings in the via region 306, a dielectric material338 may be formed along sidewalls defining the holes through the stack304. The dielectric material 338 may include the same material as thefirst dielectric material 332. In some embodiments, the dielectricmaterial 338 may include silicon dioxide. After forming the dielectricmaterial 338 in the openings in the via region 306, the conductivematerial 336 may be formed in the remaining openings to form theconductive vias 330.

Optionally, an opening may be formed between the memory array region 302and the via region 306 and filled with an insulative material 342 toform a filled trench 340. In some embodiments, the filled trench 340 maybe formed concurrently with forming the openings of the memory cellpillars 308 and the conductive vias 330.

FIG. 6B is a cross-sectional view of the semiconductor device 300 afterremoving the second dielectric material 333 to form a gap for conductiveaccess lines. By way of nonlimiting example, slots (e.g., slots 114(FIG. 1)) may be formed through the stack 304 and the second dielectricmaterial 333 may be removed through slots, such as by an isotropicmaterial removal process that selectively removes the second dielectricmaterial 333 relative to the first dielectric material 332, the chargetrapping material 312, and the dielectric material 338. Such isotropicremoval processes are known in the art and, therefore, are not describedin detail herein. The material removal process may form gaps between thefirst dielectric materials 332.

The gaps may be filled with a conductive material to form alternatingconductive material 334 in the via region 306 and conductive accesslines 316 in the memory array region 302. The conductive material mayinclude any of the materials described above with reference to theconductive access lines 116 and the conductive materials 134 describedabove with reference to FIG. 1 through FIG. 3. For example, theconductive material may include aluminum, copper, nickel, chromium,cobalt, ruthenium, rhodium, palladium, silver, platinum, gold, iridium,tantalum, tungsten, conductive metal nitrides (e.g., TiN, TaN, WN,etc.), conductive metal silicides (e.g., tantalum silicides, tungstensilicides, nickel silicides, titanium silicides, etc.), polysilicon, andcombinations thereof. In some embodiments, the conductive material mayinclude tungsten.

Since the second dielectric material 333 is replaced with the conductiveaccess lines 316 and the conductive materials 334, the process may bereferred to as a so-called “gate replacement” process.

After forming the conductive access lines 316 and the conductivematerials 334, conductive lines (e.g., the first conductive lines 144(FIG. 2) and the second conductive lines 146 (FIG. 2) may be formed. Forexample, first conductive lines may be formed in electricalcommunication with a first group of conductive vias 330 and secondconductive lines may be formed in electrical communication with a secondgroup of conductive vias 330. In some embodiments, a dielectric materialmay be formed over the semiconductor device 300 and patterned to formopenings over the conductive vias 130. A first electrically conductivelead (e.g., first electrically conductive lead 148 (FIG. 2)) may beformed in electrical contact with the first group of the conductive vias330 through the first conductive lines and a second electricallyconductive lead (e.g., second electrically conductive lead 150 (FIG. 2))may be formed in electrical contact with the second group of theconductive vias 330 through the second conductive lines. The firstelectrically conductive lead may be operably coupled to a firstcomponent of the semiconductor device and the second electricallyconductive lead may be operably coupled to a second component of thesemiconductor device to capacitively couple the first component and thesecond component.

Although the method described above with reference to FIG. 6A and FIG.6B has been described as including forming a stack 304 including thealternating first dielectric materials 332 and second dielectricmaterials 333, forming the conductive vias 330 and the memory cellpillars 308, removing the second dielectric materials 333, and formingthe conductive material 334 regions and the conductive access lines 316,the disclosure is not so limited. In other embodiments, thesemiconductor device 300 may be formed by a so-called “floating gate”method wherein a stack including alternating dielectric materials andconductive materials are formed over a substrate. The conductive vias330 and the memory cell pillars 308 may be formed through the stack byanisotropically removing portions of the dielectric material and theconductive material to form holes in the stack in the via region 306 andthe memory array region 302. Thereafter, the memory cell pillars 308 maybe formed and the conductive vias 330 may be formed as described above.Such a process may be referred to as a so-called “floating gate”process.

Accordingly, in some embodiments, a method of forming a capacitorstructure in a semiconductor device comprises forming a stack comprisingalternating first dielectric materials and second dielectric materials,forming openings in the stack in a memory array region and in a viaregion of the semiconductor device, selectively removing portions of thesecond dielectric materials from the stack to form gaps between adjacentportions of the alternating first dielectric materials, forming a firstconductive material in the gaps, forming a dielectric material on asidewall of the openings in the via region, and forming a secondconductive material in the openings of the via region over thedielectric material to form conductive vias comprising a portion of acapacitor structure comprising the second conductive material, thedielectric material on the sidewall of the conductive via, and the firstconductive material.

FIG. 7 is a simplified schematic of a system 400 that may include one ormore of the semiconductor devices 100, 300 described above. The system400 may also include additional elements, such as communicationcircuitry 410, drivers 420, a memory controller 430, an amplifier 440,and a decoder 450, for example. In some embodiments, one or more of theadditional elements may be formed under the semiconductor devices 100,300 and electrically contacted using through-array vias. A semiconductorsystem may include the system 400 as described herein.

With reference to FIG. 8, depicted is a processor-based system 800. Theprocessor-based system 800 may include various electronic devicesmanufactured in accordance with embodiments of the present disclosure.The processor-based system 800 may be any of a variety of types such asa computer, camera, pager, cellular phone, wireless device, display,chip set, set-top box, personal organizer, control circuit, or otherelectronic device. The processor-based system 800 may include one ormore processors 802, such as a microprocessor, to control the processingof system functions and requests in the processor-based system 800. Theprocessor 802 and other subcomponents of the processor-based system 800may include or be coupled to memory cells, memory arrays, andsemiconductor devices including the semiconductor devices 100, 300described herein in accordance with embodiments of the presentdisclosure.

The processor-based system 800 may include a power supply 804 inoperable communication with the processor 802. For example, if theprocessor-based system 800 is a portable system, the power supply 804may include one or more of a fuel cell, a power scavenging device,permanent batteries, replaceable batteries, and rechargeable batteries.The power supply 804 may also include an AC adapter; therefore, theprocessor-based system 800 may be plugged into a wall outlet, forexample. The power supply 804 may also include a DC adapter such thatthe processor-based system 800 may be plugged into a vehicle cigarettelighter receptacle or a vehicle power port, for example.

Various other devices may be coupled to the processor 802 depending onthe functions that the processor-based system 800 performs. For example,a user interface 806 may be coupled to the processor 802. The userinterface 806 may include input devices such as buttons, switches, akeyboard, a light pen, a mouse, a digitizer and stylus, a touch screen,a voice recognition system, a microphone, or a combination thereof. Adisplay 808 may also be coupled to the processor 802. The display 808may include a liquid crystal display (LCD), a surface-conductionelectron-emitter display (SED), a cathode ray tube (CRT) display, adigital light processing (DLP) display, a plasma display, an organiclight-emitting diode (OLED) display, a light emitting diode (LED)display, a three-dimensional projection, an audio display, or acombination thereof. Furthermore, an RF sub-system/baseband processor810 may also be coupled to the processor 802. The RF sub-system/basebandprocessor 810 may include an antenna that is coupled to an RF receiverand to an RF transmitter (not shown). A communication port 812, or morethan one communication port 812, may also be coupled to the processor802. The communication port 812 may be adapted to be coupled to one ormore peripheral devices 814, such as a modem, a printer, a computer, ascanner, or a camera, or to a network, such as a local area network,remote area network, intranet, or the Internet, for example.

The processor 802 may control the processor-based system 800 byimplementing software programs stored in the memory. The softwareprograms may include an operating system, database software, draftingsoftware, word processing software, media editing software, or mediaplaying software, for example. The memory is operably coupled to theprocessor 802 to store and facilitate execution of various programs. Forexample, the processor 802 may be coupled to system memory 816, whichmay include one or more types of volatile memory, such as dynamic randomaccess memory (DRAM). The system memory 816 may further include othertypes of volatile memory, non-volatile memory, or a combination thereof.In some embodiments, the system memory 816 may include semiconductordevices, such as the semiconductor devices including memory cells andmemory arrays including the capacitor structures 200 (FIG. 5A, FIG. 5B).

The processor 802 may also be coupled to non-volatile memory 818. Thenon-volatile memory 818 may include one or more of STT-MRAM, MRAM,read-only memory (ROM) such as an EPROM, resistive read-only memory(RROM), and Flash memory (e.g., 3D NAND) to be used in conjunction withthe system memory 816. The size of the non-volatile memory 818 istypically selected to be just large enough to store any necessaryoperating system, application programs, and fixed data. Additionally,the non-volatile memory 818 may include a high capacity memory such asdisk drive memory, such as a hybrid-drive including resistive memory orother types of non-volatile solid-state memory, for example.

Accordingly, in some embodiments, an electronic system comprisesprocessor, a semiconductor device operably coupled to the processor, anda power supply in operable communication with the processor. Thesemiconductor device includes a capacitor structure comprising a firstset of capacitors comprising a first group of conductive vias extendingthrough a stack of conductive materials and dielectric materials, asecond set of capacitors comprising a second group of conductive viasextending through the stack, wherein each conductive via of the firstgroup of conductive vias and the second group of conductive viascomprises a dielectric liner on a sidewall thereof and a conductivematerial filling the conductive via, a first electrically conductivelead in electrical communication with the first set of capacitors, and asecond electrically conductive lead in electrical communication with thesecond set of capacitors.

While certain illustrative embodiments have been described in connectionwith the figures, those of ordinary skill in the art will recognize andappreciate that embodiments encompassed by the disclosure are notlimited to those embodiments explicitly shown and described herein.Rather, many additions, deletions, and modifications to the embodimentsdescribed herein may be made without departing from the scope ofembodiments encompassed by the disclosure, such as those hereinafterclaimed, including legal equivalents. In addition, features from onedisclosed embodiment may be combined with features of another disclosedembodiment while still being encompassed within the scope of thedisclosure.

What is claimed is:
 1. A device, comprising: a stack structurecomprising alternating levels of a dielectric material and a conductivematerial; and vias located within a via region of the stack structureand extending through at least a portion of the stack structure, thevias comprising a dielectric material and a conductive material on thedielectric material, the dielectric material of the vias electricallyinsulating the conductive material of the vias from all of theconductive materials of the stack structure.
 2. The device of claim 1,wherein the conductive material of the vias comprises a materialselected from the group consisting of aluminum, copper, nickel,chromium, cobalt, ruthenium, rhodium, palladium, silver, platinum, gold,iridium, tantalum, and tungsten.
 3. The device of claim 1, wherein thevias are isolated from a memory array region of the device by one ormore trenches comprising an insulative material.
 4. The device of claim1, wherein the vias contact a source material.
 5. The device of claim 1,wherein the vias are arranged in rows and columns.
 6. The device ofclaim 1, wherein at least one via of the vias is in electricalcommunication with at least another of the vias.
 7. The device of claim1, wherein the conductive material of the vias comprises the samematerial composition as the conductive material of the alternatinglevels of the stack structure.
 8. The device of claim 1, wherein thedielectric material of the vias has a thickness between about 10 nm andabout 50 nm.
 9. An electronic device, comprising: an input device; anoutput device; a processor device operably coupled to the input deviceand the output device; and a semiconductor device operably coupled tothe processor device, the semiconductor device comprising: a stackstructure comprising alternating conductive materials and dielectricmaterials arranged in tiers, the tiers individually comprising one ofthe conductive materials and one of the dielectric materials; and viasextending through the stack structure, the vias each comprising: adielectric liner extending vertically through the stack structure andcontacting the conductive materials and the dielectric materials of thestack structure; and a conductive material extending through the stackstructure adjacent to the dielectric liner, the conductive material ofthe vias spaced from the dielectric materials by the dielectric liner.10. The electronic device of claim 9, wherein the stack structurecomprises at least about 16 tiers.
 11. The electronic device of claim 9,wherein the vias comprise a portion of a decoupling capacitor.
 12. Theelectronic device of claim 9, wherein the conductive material of thevias extends at least about 4 μm into the stack structure.
 13. Theelectronic device of claim 9, wherein the vias comprise a first group ofvias isolated from a second group of vias by another dielectricmaterial.
 14. The electronic device of claim 9, wherein the vias overliea source material.
 15. The electronic device of claim 9, wherein thevias are isolated from memory cell pillars of a NAND structure.
 16. Adevice, comprising: a stack structure comprising alternating levels of aconductive material and an insulative material; a first group ofcapacitor structures comprising vias extending into the stack structure,the first group of capacitor structures comprising: first vias extendingthrough the stack structure, the first vias comprising a firstdielectric material and a first conductive material, the firstconductive material of the first vias isolated from the levels of theconductive material of the stack structure by the first dielectricmaterial; and a second group of capacitor structures comprising viasextending into the stack structure and arranged in series with the firstgroup of capacitor structures, the second group of capacitor structurescomprising: second vias extending through the stack structure, thesecond vias comprising a second dielectric material and a secondconductive material, the second conductive material isolated from thelevels of the conductive material of the stack structure by the seconddielectric material.
 17. The device of claim 16, wherein the first viasare physically isolated from the second vias.
 18. The device of claim16, wherein the first conductive material of the first vias comprisestungsten.
 19. The device of claim 16, wherein the first vias and thesecond vias are separated from memory cell pillars comprising NANDstructures by a trench comprising another insulative material.
 20. Thedevice of claim 16, wherein the first conductive material of the firstvias and the second conductive material of the second vias contact asource material underlying the stack structure.